Pathways of sphingolipid metabolism provide a very rich network of bioactive molecules whose emerging functions suggest key roles in the regulation of cell function. In particular, published and preliminary results suggest the global hypothesis that ceramide functions as a tumor suppressor lipid, that can regulate apoptosis, senescence, and/or migration. As such, pathways of ceramide metabolism play key roles in cancer pathobiology and the response to anti-cancer and other stress agents. On the other hand, the sphingolipid sphingosine-1-phosphate (S1P) is emerging as a tumor promoting lipid with anti-apoptotic, antisenescence, pro-migration, and pro-angiogenic functions. The study of bioactive lipids is fraught with difficulties and thus necessitates the collaborative interactions of various disciplines and specialized cores. Thus, the overall hypothesis will be approached through the activities of 4 distinct projects: Project 1 will address the specific hypothesis that the acid sphingomyelinase/ceramide pathway is an important mediator of stress inducers, with key roles in regulating cancer cell migration. Project 2 will test the specific hypothesis that acid ceramidase plays an important role in controlling the dynamic balance of cellular levels of ceramide and S1P with direct consequences for novel anti-cancer therapeutics. Project 3 will test the hypothesis that sphingosine kinase 1 (SK1) proteolysis/knock-down mediates, at least part of, p53 tumor suppressor function, and that the SK1/S1P pathway mediates/participates in null/mutant p53-induced cancer. Project 4 will test the hypothesis that that LASS6-generated C16-(dihydro)ceramide plays important roles in the regulation of ER homeostasis, such that down-regulation of this pathway mediates a significant component of the ER stress response. These 4 projects will be supported by an Administrative Core, by a unique Lipidomics Core that will provide analytical and synthetic lipid chemistry, and by an Animal Core that focuses on mutants/knock outs in enzymes of sphingolipid metabolism and models of carcinogenesis. The results from these interactive studies would bring this last frontier of cellular biochemistry (sphingolipid metabolism) into cancer biology research, generating significant and unique insights into cancer cell biology and therapeutics. Ongoing studies have already resulted in the identification of novel strategies for cancer therapeutics based on novel sphingolipid-based compounds that target specific enzymes.